‘We’ve done all we can to manage the city’s finances in the most responsible manner possible,” Mayor Bloomberg said Sunday night in his final budget speech. If so, we’re all in trouble.

But just because Bloomberg hasn’t been most responsible doesn’t mean there aren’t plenty of less fiscally responsible wannabes waiting to take his place.

Voters elected Bloomberg because they were too terrified to let a Democrat take over after 9/11 — and re-elected him to a third term for the same reason after the financial crisis.

As Ronald Lauder, the billionaire who got the two-term limits passed in 1993, wrote in 2008 by way of giving Bloomberg a pass: “A city poised on the brink of economic disaster” needs “a mayor with a deep understanding of finance.” You wouldn’t know we have that mayor.

In 2002, city-funded spending was $26.4 billion. In the budget for the fiscal year that starts next week, spending will be $53.7 billion — twice as much. We spend $19 billion more than if the budget had kept up with inflation. Over the mayor’s third term, spending is up 17 percent — nearly twice inflation.

The culprits, as everyone knows, are public-employee benefits. Next year, the city will spend $17.1 billion on pensions, health care and other “fringe” benefits — 12 times what it will spend on welfare.

Everyone knows — except the Democrats who want to be mayor. Standing with the mayor Sunday was City Council Speaker Christine Quinn. You’d think she’d strike a sober note. If she’s mayor next year, she’ll face a $2 billion deficit. Here was her last chance to blame Bloomberg. (She’s signed off on the last eight budgets, so it’s her fault, too — but some fiscal awareness would be better late than never.)

But she was rosy. “We now have a better outlook than we had at any time since the financial crash of 2008,” said Quinn. Any problems, she blamed on the feds. “We are faced with challenges because of what the federal government has failed to do,” she said.

Curious statement. The federal government has helped New York more than it has hurt over the past five years — most specifically through zero-percent interest rates. Banks can borrow nearly for free and make money speculating. New York faces big budget risks now because the Fed may soon raise rates.

But costs aren’t going down as interest rates go up. Toward the end of the next mayor’s first term, pensions and health care will run $19.7 billion annually — 33 percent of city-funded spending (up from 22 when the mayor took office). And as interest rates rise, the next mayor will face another crunch: It will cost more to borrow.

But other Democratic contenders criticized Bloomberg (and Quinn) for not spending enough.

Public Advocate Bill de Blasio said City Hall should have “provided pre-K for every child” by raising taxes on people making more than half a million dollars. Britain tried to raise taxes on the rich two years ago, but backtracked when the data showed that the result “could be negative” as people shifted their income to avoid the taxes, its treasury said.

Comptroller John Liu slammed the mayor for leaving “the biggest question — expired labor contracts — for another mayor and another day.” But workers can’t get retroactive raises, because the city can’t afford them.

Bill Thompson and Anthony Weiner stayed quiet. Thompson may not want to annoy his new patron, the United Federation of Teachers. Fresh from endorsing the former comptroller, union chief Michael Mulgrew accused Bloomberg of playing a “confidence game” in hiding budget surpluses — ignoring the fact that six of the past seven budgets have been in deficit. The only “surplus” was from before Lehman Brothers collapsed, and that $8 billion is gone.

If the candidates are playing make-believe, it’s partly due to lack of adult supervision. Bloomberg is supposed to be the guy with the “deep understanding of finance.” Yet he didn’t use his final budget speech to sound alarms.

True, that would mean admitting fiscal defeat. But the next mayor could turn defeat into disaster.

Nicole Gelinas is a contributing editor to the Manhattan Institute’s “